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Old 08-28-2013, 06:28 PM   #1
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Question on LJ regearing, and lift/driveshaft

I've been a forum lurker for a while, and doing as much research as I can.

First off, I've got an '05 Wrangler Unlimited. 3.73 gearing,, 6 speed manual, 30" tires and 15" rims, completely stock. I'm looking into throwing on some bigger tires, and a lift. So, here are my more specific questions.

First, why should I (or, shouldn't I) regear? Initially it looked like I wanted to go to 4.10, now maybe 4.88. But again, why not leave it at 3.73? It's a daily driving Jeep, that I'll take on some off roading, but nothing too crazy just yet. What do I gain from regearing, and what do I lose? All I can find is if I leave it at 3.73 it'll "be a dog", does that mean it'll accelerate slowly, and not take hills well? First gear is already pretty jumpy IMO. So I'm just wondering, since it's primarily a road vehicle and any off roading will be light for now, is the regearing necessary for my uses of it, and if so, what ratio?

Next, how much lift can I go without needing a new driveshaft? I know, tis question has probably been done to death, and I usually see around 3", and that all Jeeps are different. My biggest question is that since mine is an Unlimited, can I go a little higher than a standard TJ? And if so, how much? Don't get me wrong, I will have a SYE and driveshaft in the budget, but if I don't have to buy them, I'd be happier. And with that, how good (or bad) is a transfer case drop?

Those are the two big questions, I suppose. I'll also mention that I'm planning on going with BF Goodrich All Terrains, 35"X12.5"X15" on Pro Comp Alloy Rims. For a lift, I was thinking of a 4" either Teraflex or Zone lift, and maybe a 1" body lift if necessary. If I can only get away with 3" without a SYE and driveshaft, I'll probably do that.

I'm not trying to skimp here, but I also don't want to spend more than I have to, on stuff that isn't necessary for what I'll be doing. I don't need the meanest suspension system just yet, because I won't be doing any aggressive offroading just yet. When that day comes (a few years down the road) I'll get a bigger, and better one. And if the higher gearing is for crawling, then I don't think I'll do it just yet.

Thanks for the help, it's always appreciated.

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Old 08-28-2013, 06:30 PM   #2
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Old 08-28-2013, 06:41 PM   #3
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Ah ha, thank you kindly good sir. I read that post a long time ago, but before I knew what it meant. So I gather that with an LJ, I should be okay with a 4" lift and no SYE and drive shaft, but anything more than that and I'm pushing my luck.
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Old 08-28-2013, 07:15 PM   #4
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Most likely yes. But 4" is pushing it.
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Old 08-28-2013, 07:46 PM   #5
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Okay, I won't go any more than that without the SYE and driveshaft. Now I just gotta find out about the gearing.
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Old 08-28-2013, 08:11 PM   #6
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At least 4.88 for 35
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Old 08-28-2013, 08:35 PM   #7
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Not trying to be difficult, but why? I just don't understand what will be the affect on my Jeep if I keep it at 3.73. Will I lose fuel efficiency, acceleration, top speed?
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Old 08-28-2013, 08:39 PM   #8
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Quote:
Originally Posted by Thunder Mass View Post
Not trying to be difficult, but why? I just don't understand what will be the affect on my Jeep if I keep it at 3.73. Will I lose fuel efficiency, acceleration, top speed?
essentially, you'll lose 6th gear. you'll lose fuel economy, acceleration, crawl ratio, highway drive-ability.

for the 6-speed, 35s and 4.56's or 4.88s would be well matched.

regardless of your decision, if you change gear ratios or tire size, you need to fix the speedometer calibration.

also, 35's need a host of other stuff too....like a big brake kit, steering upgrades, and a whole bunch of suspension work.
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Old 08-28-2013, 09:36 PM   #9
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I also have a 05 Lj. After tons of research I decided to go with 33s when I do
It. So many things need to
Upgrade for 35s I can't justify the cost.
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Old 08-29-2013, 12:04 AM   #10
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Quote:
Originally Posted by Thunder Mass View Post
why should I (or, shouldn't I) regear?
should: regain lost performance
shouldn't: if cost is personally prohibitive

Quote:
Originally Posted by Thunder Mass View Post
Initially it looked like I wanted to go to 4.10
waste of money - not enough of a difference

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Originally Posted by Thunder Mass View Post
now maybe 4.88
that's the lowest (numerically) I'd go.

Quote:
Originally Posted by Thunder Mass View Post
But again, why not leave it at 3.73?
you can always do the lift and tires and drive it for a while to see how you like it

Quote:
Originally Posted by Thunder Mass View Post
It's a daily driving Jeep, that I'll take on some off roading, but nothing too crazy just yet.
on-road is where you'll appreciate the regear the most

Quote:
Originally Posted by Thunder Mass View Post
What do I gain from regearing, and what do I lose?
gain: lost performance
lose: money

Quote:
Originally Posted by Thunder Mass View Post
All I can find is if I leave it at 3.73 it'll "be a dog", does that mean it'll accelerate slowly, and not take hills well?
yes

Quote:
Originally Posted by Thunder Mass View Post
So I'm just wondering, since it's primarily a road vehicle and any off roading will be light for now, is the regearing necessary for my uses of it, and if so, what ratio?
necessary? no
recommended? yes
ratio: 4.88 or 5.13 - refer to one of the gearing calculators to see what rpms you'll be turning at a given speed

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And with that, how good (or bad) is a transfer case drop?
IMO = bad. I don't get the idea of lifting a Jeep and at the same time lowering the transfer case/shovel.
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Old 08-29-2013, 07:29 AM   #11
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I have an 05 LJ, manual
It's my DD and occasional offroader for moderate trails.
I run a 3" lift, no BL.
33x10.50 MTs on15x7" wheels, 3.75 bs, Rubi flares. No rubbing anywhere.
I haven't regeared; still running the 3.73s

It isn't too bad, you get used to it. I never use 6th unless I'm on the highway going over 60. For the other gears, I just tend to run in the gear that keeps me close to the powerband.
My fuel mileage is 13.5 local, 15 highway.
Offroad, the NSG 370 is pretty low in first, so I don't have much difficulty unless I'm trying to run big rocks. The trails I typically run are moderate... not easy, not extreme.
HTH,
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Old 08-29-2013, 08:24 AM   #12
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Not to hijack, but what about an automatic LJ and 33's? 4.56 or 4.88? Higher?
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Old 08-29-2013, 03:23 PM   #13
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410 s are fine with 33's

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